/* Copyright (c) 2010, Carl Burch. License information is located in the
 * com.cburch.logisim.Main source code and at www.cburch.com/logisim/. */

package com.cburch.logisim.std.arith;

import java.awt.Color;
import java.awt.Graphics;

import com.cburch.logisim.data.Attribute;
import com.cburch.logisim.data.BitWidth;
import com.cburch.logisim.data.Bounds;
import com.cburch.logisim.data.Direction;
import com.cburch.logisim.data.Location;
import com.cburch.logisim.data.Value;
import com.cburch.logisim.instance.InstanceFactory;
import com.cburch.logisim.instance.InstancePainter;
import com.cburch.logisim.instance.InstanceState;
import com.cburch.logisim.instance.Port;
import com.cburch.logisim.instance.StdAttr;
import com.cburch.logisim.tools.key.BitWidthConfigurator;
import com.cburch.logisim.util.GraphicsUtil;
import static com.cburch.logisim.util.LocaleString.*;

public class Multiplier extends InstanceFactory {
    static final int PER_DELAY = 1;

    private static final int IN0   = 0;
    private static final int IN1   = 1;
    private static final int OUT   = 2;
    private static final int C_IN  = 3;
    private static final int C_OUT = 4;

    public Multiplier() {
        super("Multiplier", getFromLocale("multiplierComponent"));
        setAttributes(new Attribute[] { StdAttr.WIDTH },
                new Object[] { BitWidth.create(8) });
        setKeyConfigurator(new BitWidthConfigurator(StdAttr.WIDTH));
        setOffsetBounds(Bounds.create(-40, -20, 40, 40));
        setIconName("multiplier.svg");

        Port[] ps = new Port[5];
        ps[IN0]   = new Port(-40, -10, Port.INPUT,  StdAttr.WIDTH);
        ps[IN1]   = new Port(-40,  10, Port.INPUT,  StdAttr.WIDTH);
        ps[OUT]   = new Port(  0,   0, Port.OUTPUT, StdAttr.WIDTH);
        ps[C_IN]  = new Port(-20, -20, Port.INPUT,  StdAttr.WIDTH);
        ps[C_OUT] = new Port(-20,  20, Port.OUTPUT, StdAttr.WIDTH);
        ps[IN0].setToolTip(getFromLocale("multiplierInputTip"));
        ps[IN1].setToolTip(getFromLocale("multiplierInputTip"));
        ps[OUT].setToolTip(getFromLocale("multiplierOutputTip"));
        ps[C_IN].setToolTip(getFromLocale("multiplierCarryInTip"));
        ps[C_OUT].setToolTip(getFromLocale("multiplierCarryOutTip"));
        setPorts(ps);
    }

    @Override
    public void propagate(InstanceState state) {
        // get attributes
        BitWidth dataWidth = state.getAttributeValue(StdAttr.WIDTH);

        // compute outputs
        Value a = state.getPort(IN0);
        Value b = state.getPort(IN1);
        Value c_in = state.getPort(C_IN);
        Value[] outs = Multiplier.computeProduct(dataWidth, a, b, c_in);

        // propagate them
        int delay = dataWidth.getWidth() * (dataWidth.getWidth() + 2) * PER_DELAY;
        state.setPort(OUT,   outs[0], delay);
        state.setPort(C_OUT, outs[1], delay);
    }

    @Override
    public void paintInstance(InstancePainter painter) {
        Graphics g = painter.getGraphics();
        painter.drawBounds();

        g.setColor(Color.GRAY);
        painter.drawPort(IN0);
        painter.drawPort(IN1);
        painter.drawPort(OUT);
        painter.drawPort(C_IN,  "c in",  Direction.NORTH);
        painter.drawPort(C_OUT, "c out", Direction.SOUTH);

        Location loc = painter.getLocation();
        int x = loc.getX();
        int y = loc.getY();
        GraphicsUtil.switchToWidth(g, 2);
        g.setColor(Color.BLACK);
        g.drawLine(x - 15, y - 5, x - 5, y + 5);
        g.drawLine(x - 15, y + 5, x - 5, y - 5);
        GraphicsUtil.switchToWidth(g, 1);
    }


    static Value[] computeProduct(BitWidth width, Value a, Value b, Value c_in) {
        int w = width.getWidth();
        if (c_in == Value.NIL || c_in.isUnknown()) {
            c_in = Value.createKnown(width, 0);
        }

        if (a.isFullyDefined() && b.isFullyDefined() && c_in.isFullyDefined()) {
            long sum = (long) a.toIntValue() * (long) b.toIntValue()
                + c_in.toIntValue();
            return new Value[] { Value.createKnown(width, (int) sum),
                Value.createKnown(width, (int) (sum >> w)) };
        } else {
            Value[] avals = a.getAll();
            int aOk = findUnknown(avals);
            int aErr = findError(avals);
            int ax = getKnown(avals);
            Value[] bvals = b.getAll();
            int bOk = findUnknown(bvals);
            int bErr = findError(bvals);
            int bx = getKnown(bvals);
            Value[] cvals = c_in.getAll();
            int cOk = findUnknown(cvals);
            int cErr = findError(cvals);
            int cx = getKnown(cvals);

            int known = Math.min(Math.min(aOk, bOk), cOk);
            int error = Math.min(Math.min(aErr, bErr), cErr);
            int ret = ax * bx + cx;

            Value[] bits = new Value[w];
            for (int i = 0; i < w; i++) {
                if (i < known) {
                    bits[i] = ((ret & (1 << i)) != 0 ? Value.TRUE : Value.FALSE);
                } else if (i < error) {
                    bits[i] = Value.UNKNOWN;
                } else {
                    bits[i] = Value.ERROR;
                }
            }
            return new Value[] { Value.create(bits),
                    error < w ? Value.createError(width) : Value.createUnknown(width) };
        }
    }

    private static int findUnknown(Value[] vals) {
        for (int i = 0; i < vals.length; i++) {
            if (!vals[i].isFullyDefined()) {
                return i;
            }

        }
        return vals.length;
    }

    private static int findError(Value[] vals) {
        for (int i = 0; i < vals.length; i++) {
            if (vals[i].isErrorValue()) {
                return i;
            }

        }
        return vals.length;
    }

    private static int getKnown(Value[] vals) {
        int ret = 0;
        for (int i = 0; i < vals.length; i++) {
            int val = vals[i].toIntValue();
            if (val < 0) {
                return ret;
            }

            ret |= val << i;
        }
        return ret;
    }
}
